William N. Levine

Shoulder Motion and Laxity in the Professional Baseball Player

We studied 148 professional baseball players with no history of shoulder problems to assess range of motion and laxity of their dominant and nondominant shoul ders. There were 72 pitchers and 76 position players. Average external rotation with the arm in 90° of abduc tion was statistically greater and average internal rota tion was statistically less in the dominant shoulders than in the nondominant shoulders, both in pitchers and position players. There was no statistical differ ence in forward elevation or external rotation with the arm at the side of the body in either group. Both dom inant and nondominant shoulders of pitchers had greater average range of motion in forward elevation and external rotation (both at the side and at 90° of abduction) and less average internal rotation than those of position players. Regarding laxity testing, 61 % of dominant shoulders in pitchers had a sulcus sign, as compared with 47% in position players. Also, this de gree of inferior laxity was significantly greater in pitch ers than in position players. Differences in range of motion and laxity exist in the throwing shoulder of athletes involved in overhead throwing motions and should be considered in rehabilitation protocols and surgical repair.

Novel Nanofiber-Based Scaffold for Rotator Cuff Repair and Augmentation

The debilitating effects of rotator cuff tears and the high incidence of failure associated with current grafts underscore the clinical demand for functional solutions for tendon repair and augmentation. To address this challenge, we have designed a poly(lactide-co-glycolide) (PLGA) nanofiber-based scaffold for rotator cuff tendon tissue engineering. In addition to scaffold design and characterization, the objective of this study was to evaluate the attachment, alignment, gene expression, and matrix elaboration of human rotator cuff fibroblasts on aligned and unaligned PLGA nanofiber scaffolds. Additionally, the effects of in vitro culture on scaffold mechanical properties were determined over time. It has been hypothesized that nanofiber organization regulates cellular response and scaffold properties. It was observed that rotator cuff fibroblasts cultured on the aligned scaffolds attached along the nanofiber long axis, whereas the cells on the unaligned scaffold were polygonal and randomly oriented. Moreover, distinct integrin expression profiles on these two substrates were observed. Quantitative analysis revealed that cell alignment, distribution, and matrix deposition conformed to nanofiber organization and that the observed differences were maintained over time. Mechanical properties of the aligned nanofiber scaffolds were significantly higher than those of the unaligned, and although the scaffolds degraded in vitro, physiologically relevant mechanical properties were maintained. These observations demonstrate the potential of the PLGA nanofiber-based scaffold system for functional rotator cuff repair. Moreover, nanofiber organization has a profound effect on cellular response and matrix properties, and it is a critical parameter for scaffold design.

Mechanical Properties of Soft Tissue Femoral Fixation Devices for Anterior Cruciate Ligament Reconstruction

Purpose To evaluate femoral soft tissue fixation for anterior cruciate ligament reconstruction. Hypothesis Femoral fixation devices have different ultimate strengths and slippage under cyclic loading. Study Design Controlled laboratory study. Methods Thirty-three porcine femora were used to study interference screw (9), Endobutton (8), Rigidfix cross-pin (8), and Bio-Transfix cross-pin (8) fixation methods. Fixation slippage was evaluated under cyclical load from 50 N to 250 N using a materials testing machine. Ultimate load was determined with a single load to failure. Results Total graft slippage was greater (P< .001) for the Rigidfix (6.02 ± 2.12 mm) and the interference screw (5.44 ± 3.25 mm) compared to the Endobutton (1.75 ± 0.97 mm) and the Bio-Transfix (1.14 ± 0.53 mm). All techniques showed the greatest slippage during the first 100 cycles (Rigidfix 84%, Endobutton 70%, interference screw 56%, and Bio-Transfix 55%). The failure load for the interference screw technique (539 ± 114 N) was lower (P= .0008) than for the other 3 techniques (737 ± 140 N for Rigidfix, 746 ± 119 N for Bio-Transfix, and 864 ± 164 N for Endobutton). Conclusions The interference screw and the Rigidfix fixation demonstrated inferior fixation biomechanics compared to the Bio-Transfix and the Endobutton techniques.

Current Concepts Review - Subacromial Impingement Syndrome*

In the last two decades, subacromial impingement syndrome has become an increasingly common diagnosis for patients who have a painful shoulder. However, subacromial impingement syndrome is a specific diagnosis and is not the only cause of pain in the anterosuperior aspect of the shoulder. Impingement may be difficult to diagnose because the clinical presentation may be confusing. It is important to differentiate subacromial impingement syndrome from other conditions that may cause symptoms in the shoulder, such as glenohumeral instability, cervical radiculitis, calcific tendinitis, adhesive capsulitis, degenerative joint disease, isolated acromioclavicular osteoarthrosis, and nerve compression. This is particularly true when examining younger patients, especially athletes who perform overhead motions with use of the upper extremity, in whom the diagnosis of impingement should be made with caution. In many cases, the primary diagnosis is subtle glenohumeral instability even though impingement and subacromial bursitis are evident. In the past, many authors noted abnormal contact between the coracoacromial arch and the rotator cuff tendons6,18,23,63,66,71-73, but the exact etiology was not clearly understood. Meyer66, in 1931, proposed that tears of the rotator cuff occurred secondary to attrition as a result of friction with the undersurface of the acromion. He described corresponding lesions on the undersurface of the acromion and the greater tuberosity, although he did not implicate the acromion directly. Codman18, in 1934, defined the critical zone, where most degenerative changes occur, as a portion of the rotator cuff located one centimeter medial to the insertion of the supraspinatus on the greater tuberosity. Armstrong6, in 1949, introduced the term supraspinatus syndrome and proposed that the condition should be treated with a total acromionectomy. Diamond23 also noted the role of the acromion as a cause …

Tendon-to-Bone Pressure Distributions at a Repaired Rotator Cuff Footprint Using Transosseous Suture and Suture Anchor Fixation Techniques

Background Interface contact pressure between the tendon and bone has been shown to influence healing. This study evaluates the interface pressure of the rotator cuff tendon to the greater tuberosity for different rotator cuff repair techniques. Hypothesis The transosseous tunnel rotator cuff repair technique provides larger pressure distributions over a defined insertion footprint than do suture anchor techniques. Study Design Controlled laboratory study. Methods Simulated rotator cuff tears over a 1 × 2-cm infraspinatus insertion footprint were created in 25 bovine shoulders. A transosseous tunnel simple suture technique (n = 8), suture anchor simple technique (n = 9), and suture anchor mattress technique (n = 8) were used for repair. Pressurized contact areas and mean pressures of the repaired tendon against the tuberosity were determined using pressure-sensitive film placed between the tendon and the tuberosity. Results The mean contact area between the tendon and tuberosity insertion footprint was significantly greater for the transosseous technique (67.7 ± 5.8 mm2) compared with the suture anchor simple (34.1 ± 9.4 mm2) and suture anchor mattress (26.0 ±5.3 mm2) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was also greater for the transosseous technique (0.32 ± 0.05 MPa) compared with the suture anchor simple (0.26 ± 0.04 MPa) and suture anchor mattress (0.24 ± 0.02 MPa) techniques (P < .05). Conclusion The transosseous tunnel rotator cuff repair technique creates significantly more contact and greater overall pressure distribution over a defined footprint when compared with suture anchor techniques. Clinical Relevance Stronger and faster rotator cuff healing may be expected when beneficial pressure distributions exist between the repaired rotator cuff and its insertion footprint. Tendon-to-tuberosity pressure and contact characteristics should be considered in the development of improved open and arthroscopic rotator cuff repair techniques.

Glenoid Bone Deficiency in Recurrent Anterior Shoulder Instability: Diagnosis and Management

&NA; Recurrent anterior shoulder instability may result from a spectrum of overlapping, often coexistent factors, one of which is glenoid bone loss. Untreated, glenoid bone loss may lead to recurrent instability and poor patient satisfaction. Recent studies suggest that the glenoid rim is altered in up to 90% of shoulders with recurrent instability, thus underscoring the need for careful diagnosis, quantification, and preoperative evaluation. Biomechanical and clinical studies offer criteria that may be used in both primary and revision settings to judge whether shoulder stability is compromised by a bony defect. Along with patient activity level, these criteria can help guide the surgeon in selecting treatment options, which range from nonsurgical care to isolated soft‐tissue repair as well as various means of bony reconstitution.

Two-part and three-part fractures of the proximal humerus treated with suture fixation.

Objective To evaluate the radiographic and clinical outcomes of patients with displaced proximal humerus fractures (two-part and three-part) treated with nonabsorbable rotator cuff–incorporating sutures. Design Retrospective. Setting University hospital. Patients There were 27 patients (28 shoulders) with displaced proximal humerus fractures. There were 13 greater tuberosity (GT) and 9 surgical neck (SN) two-part fractures and 6 GT/SN three-part fractures. The average age was 64 years (range 38 to 84 years). The average follow-up was 4.4 years (range 1.0 to 11.5 years). Intervention All patients were surgically treated solely with heavy polyester nonabsorbable sutures. Main Outcome Measurements Functional assessment was obtained using the American Shoulder and Elbow Surgeons (ASES) score and Neers criteria, which grade outcomes as excellent, satisfactory, or unsatisfactory. Results Overall, there were 22 (78%) excellent, 3 (11%) satisfactory, and 3 (11%) unsatisfactory results, and the average ASES score was 87.1 (range 35.0 to 100.0). All shoulders healed radiographically without evidence of avascular necrosis of the humeral head. Twenty-four shoulders (86%) had anatomic alignment on postoperative radiographs. Of four shoulders with nonanatomic alignment, three had ASES scores of ≥90, with excellent Neer scores. When comparing patients with isolated two-part GT fractures (n = 13) with patients having two-part SN or three-part SN/GT fractures (n = 15), there were no statistically significant differences with respect to range of motion (P > 0.05) and outcome measures (P > 0.05). All patients who had unsatisfactory outcomes were noncompliant with physical therapy, with ASES scores averaging 39.4 (range 35.0 to 43.3). Conclusion Two-part and three-part GT and SN fractures can be treated satisfactorily with heavy nonabsorbable rotator cuff–incorporating sutures, particularly in elderly patients. Hardware-associated complications are obviated. Patients with SN fractures treated with sutures can have outcomes similar to patients with two-part GT fractures. Although the goal is to reconstruct a “one-part” fracture pattern, some residual deformity does not preclude an excellent outcome. A compliant patient is crucial for a successful result.

Chondrolysis following arthroscopic thermal capsulorrhaphy to treat shoulder instability : A report of two cases

Despite the paucity of long-term supportive studies, the use of thermal energy for the treatment of shoulder instability has become increasingly popular during the last decade. Axillary nerve injury, recurrent instability, capsular obliteration, and adhesive capsulitis are known complications of thermal capsulorrhaphy that have been documented in the literature1-5. A recent report highlighted the complication of chondrolysis following shoulder arthroscopy in three patients6; however, none of these patients had chondrolysis severe enough to warrant arthroplasty. We present the cases of two young athletes who had severe chondrolysis following thermal capsulorrhaphy for the treatment of shoulder instability. Our patients were informed that data concerning each case would be submitted for publication. Case 1. A nineteen-year-old right-hand-dominant competitive gymnast and diver presented with symptoms of left-sided shoulder instability, which had first developed when he was fifteen years of age and had been treated conservatively for three years; he had no dislocations. Physical examination demonstrated 2+ anterior load and shift, 2+ posterior load and shift, a 2+ sulcus sign7, positive apprehension and relocation tests, and no signs of generalized ligamentous laxity. A magnetic resonance imaging-arthrogram demonstrated a normal glenohumeral joint and a patulous capsule (Fig. 1). Despite nonoperative management, including activity modification, physical therapy, and treatment with anti-inflammatory medications, the instability pattern persisted and the patient elected to proceed with arthroscopic surgery. The intraoperative findings demonstrated a patulous capsular pouch. The treating surgeon believed that thermal capsulorrhaphy was indicated on the basis of the preoperative examination and the intraoperative findings and treated the capsule thermally with the “zebra-striping” technique, which is designed to leave normal strips of capsular tissue intertwined with the thermally altered tissue. A monopolar radiofrequency device (Oratec ORA-50; Oratec Interventions, Menlo Park, California) was used with the standard settings of 67°C …

The Pathophysiology of Shoulder Instability

Over the last several decades there has been an improved understanding of the intricate anatomy that provides stability to the glenohumeral joint. In addition, significant advances in identifying the pathologic etiology of the unstable shoulder have occurred because of basic science glenohumeral ligament cutting studies, clinical evaluation, and the advent of arthroscopic evaluation and treatment of the unstable shoulder. This article will review the pertinent anatomy of the normal glenohumeral joint and will carefully review the pathoanatomy found in the unstable shoulder. Sports medicine specialists who treat athletes with unstable shoulders should have a firm understanding of both the normal and pathologic shoulder conditions to be able to provide the best care for these athletes.

Patellofemoral stresses during open and closed kinetic chain exercises: An analysis using computer simulation

Rehabilitation of the symptomatic patellofemoral joint aims to strengthen the quadriceps muscles while limiting stresses on the articular cartilage. Some investigators have advocated closed kinetic chain exercises, such as squats, because open kinetic chain exercises, such as leg extensions, have been suspected of placing supraphysiologic stresses on patellofemoral cartilage. We performed computer simulations on geometric data from five cadaveric knees to compare three types of open kinetic chain leg extension exercises (no external load on the ankle, 25-N ankle load, and 100-N ankle load) with closed kinetic chain knee-bend exercises in the range of 20° to 90° of flexion. The exercises were compared in terms of the quadriceps muscle forces, patellofemoral joint contact forces and stresses, and “benefit indices” (the ratio of the quadriceps muscle force to the contact stress). The study revealed that, throughout the entire flexion range, the open kinetic chain stresses were not supraphysiologic nor significantly higher than the closed kinetic chain exercise stresses. These findings are important for patients who have undergone an operation and may feel too unstable on their feet to do closed chain kinetic chain exercises. Open kinetic chain exercises at low flexion angles are also recommended for patients whose proximal patellar lesions preclude loading the patellofemoral joint in deeper flexion.